This invention is related to cover systems for pools and spas, and more specifically, to a motorized pool cover system utilizing at least two motors.
Typically, previous pool cover systems used a complicated system of pulleys and mechanical linkages to facilitate the movement of a pool cover between an open and closed position. In the open position, the pool cover was generally stored at one end of the pool, rolled up on a drum. From each side edge of the pool cover ran a cable. These two cables traveled to the far end of the pool, generally in an enclosed track. At the far end of the pool, each cable was routed around a pulley, then routed back to the near end of the pool, where the cables were received by one or more take up reels. To move the cover from its open position to its closed position, the cables would be wound onto the reels, thereby unwinding the stored pool cover from the drum, and pulling it through the enclosed track assembly, toward the opposite end of the pool. Typically, the edges of the pool cover would follow along in the same enclosed track as the cables until the cover was stretched across the pool to the far end, in its fully closed position. The take up reels for storing the cables, and the drum for storing the pool cover typically rotated about the same axis, and sometimes were even located on a common drive shaft. In the motorized systems, a single motor was generally utilized with a clutch or transmission system so that the motor could engage either the reels or the drum, with the non-engaged component xe2x80x9cfree-wheelingxe2x80x9d. One engagement system used concentric sleeves about a shaft, linking both the reels and the drum to a common shaft and motor.
Mechanical braking systems were also utilized to maintain tension on the cover and the cables. For example, when the motor was engaged to the reels, turning the reels to wind up the cables, thereby unwinding the cover from the drum and pulling the pool cover closed, a braking system applied pressure to the drum to maintain proper tension in both the pool cover and the cables.
In other systems, a spring-biased compensator system was utilized to equalize the forces on the sides of the cover and the cables, to ensure that the cover was wound straight on the drum.
Previously, pool cover systems generally required limit switches for proper operation of the cover, to ensure that the cover would open fully or close fully, without moving too far or damaging the pool cover. When the cover passed a specified position, a limit switch was tripped and the cover was either stopped or reversed. In addition, safety systems were used to stop the movement of the cover in the event that the cover encountered an obstruction. A commonly used method was to integrate a shear pin into the drive mechanism so to limit the force which could be exerted on the cover. When an obstruction was encountered, the system would push against the obstruction until the force was great enough to break the shear pin. The system would then be inoperable until a service call was made and the shear pin replaced. Both of these systems required additional mechanical components in the cover system, as well as additional necessary electrical contacts and/or switches.
In another previous system, two motors were utilized, with one motor located at each end of the pool. This, however, necessitated below-surface installations at each end of the pool, requiring additional space, additional wiring, and generating additional costs. In addition to the need for a motor housing area at each end of the pool, this system also required that a power source for each motor be routed to each end of the pool, again increasing installation costs. Another system utilized multiple hydraulic motors, with a motor for the reel, and a motor for the drum. However, installation of a hydraulic system is generally more costly than the installation of a comparable electric system, because in addition to installing the motors, reels and drum, a hydraulic system also requires a hydraulic power source, and a distribution system for the hydraulic fluid displaced by the hydraulic power source. Typically, the piping or tubing required for the hydraulic fluid distribution system would be somewhat complicated, take up additional space, and raise reliability questions, as the hydraulic fluid distribution system would be recessed, and any leakages of hydraulic fluid would necessitate access to the recessed distribution system. In addition, given the possibility of leakage, the use of hydraulic fluids in close proximity to the swimming pool water may also cause safety concerns.
Another requirement common to most previous cover systems was the requirement of precise alignment of the drum and reel portions, to facilitate the use of a common drive shaft. Thus the time and expense of installation was increased, as the reel and drum portions had to be carefully aligned to ensure proper operation of the cover, including the drive, engagement and braking systems.
Further, given the naturally moist environment around swimming pools, the use of complicated mechanical clutches, transmissions, concentric sleeves and other engagement systems, along with mechanical braking systems, spring-equipped compensator systems, and electrical contacts and switches, could result in rusted components which may bind, seize, and/or otherwise not perform as designed. Also, with the leaves and other debris which often accumulate in pool areas, proper operation of complicated mechanical systems could be prevented by foreign objects or debris.
Thus there exists the need for a motorized pool cover system which reduces the complexity and size of the installation, eliminates the need for complicated mechanical linkages and systems such as clutches, transmissions, sleeves and brakes, and provides simple, reliable and safe operation in covering and uncovering a pool.
The present invention is embodied in a dual drive pool cover system which utilizes a first motor coupled to a drum, and a second motor coupled to a reel, both located at one end of a pool. A cover is coupled at one end to the drum, and at the other end to first and second lines, which are coupled to the cover at one end and to the reel at the other end. An electronic controller is coupled to the motors to control them and provide power. This system provides simplified installation, reduced installation space requirements, simplified operation, and increased reliability by removing unnecessary mechanical driving, braking and safety hardware, by controlling the motors simultaneously to open and close the pool cover, by automatically controlling tension, by automatically applying opening and closing limits, and by limiting the torque the motors apply to the cover, all with the motors installed in a relatively compact space at one end of the pool.
An important feature of this invention is that it reduces the space necessary for installation, as the motors are housed at one end of the pool, and preferably are small motors which are incorporated directly into the respective reel and drum assemblies.
Another important feature is the built-in tensioning system provided by the electronic motor controller. Both motors are used to open the cover, with one motor winding the cover onto the drum while the other motor unwinds the lines from the reel, providing tension as the lines leave the reel. Likewise, both motors are used to close the cover, with one motor turning the reel, thereby winding the lines onto the reel, while the other motor turns the drum, unwinding the cover and providing tension as the cover leaves the drum. The motors are electronically controlled to work together and maintain the proper tension on both the lines and the cover. In addition, by electronically controlling the motors to optimize the tension in the lines and the cover, the system minimizes the current required to open and close the pool cover.
The electronic motor controller also limits the torque the motors exert on the cover: when movement of the cover is obstructed, either during opening or closing of the cover, or when the cover reaches either its fully opened or fully closed position, the cover exerts only a specified amount of torque. The controller limits the current to the motor, thereby limiting the torque, and preventing the motor from causing damage or injury. In this same way, the controller acts as a limit switch to ensure that the cover fully opens and closes.
Another feature of the system is simplified alignment during installation. In addition to decreasing the space needed for installation, this system also decreases the time needed for installation, because the reel assembly and drum assembly are virtually self-aligning. Simple mounting assemblies attach the system to the end wall of the pool. The reel assembly and drum assembly are independently mounted, with the mounting assembly for the reel providing an adjustable mount for the drum assembly.
Another feature of the system is the simplified operation and control, and increased dependability of the electronic control loop, which utilizes a single controller to supply and adjust current to the motors, maintain tensions, and electronically control opening and closing of the cover system. The user simply chooses either open or close, and the controller regulates the simultaneous operation of the motors.
Other features and advantages of the present invention will become apparent from the following description of the preferred embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.